阅读说明：本技术 陶瓷基板多孔阵列皮秒激光振镜扫描钻孔系统及方法 (Ceramic substrate porous array picosecond laser galvanometer scanning drilling system and method ) 是由 张轲 龚朋真 于 2020-05-11 设计创作，主要内容包括：本发明提供了一种陶瓷基板多孔阵列皮秒激光振镜扫描钻孔系统及方法,包括：首先设置激光钻孔加工路径、以及激光钻孔工艺参数,钻孔时,工位滑台将陶瓷基板的待钻孔移至钻孔位置,CCD视觉对钻孔位置进行辨识和定位,振镜激光束对陶瓷基板逐层精密钻孔,同时开启烟尘抽吸和保护气,每加工一层,切割头自动下移一层加工厚度,直至加工完所有的层；然后工位滑台将工件移至下一个钻孔位置,重复进行直至钻完陶瓷基板上所有的孔。本发明陶瓷基板切割边缘光滑,圆度好、锥度更小、碎裂几率低,几乎无热影响区,边缘不发黄,对陶瓷基板几乎无损伤,良品率大大提高。(The invention provides a ceramic substrate porous array picosecond laser galvanometer scanning drilling system and a method, which comprises the following steps: firstly, setting a laser drilling processing path and laser drilling process parameters, wherein during drilling, a station sliding table moves a hole to be drilled of a ceramic substrate to a drilling position, CCD vision identifies and positions the drilling position, a vibrating mirror laser beam precisely drills the ceramic substrate layer by layer, smoke suction and protective gas are started simultaneously, and a cutting head automatically moves down one layer of processing thickness every time one layer is processed until all layers are processed; and then the work piece is moved to the next drilling position by the station sliding table, and the operation is repeated until all the holes on the ceramic substrate are drilled. The ceramic substrate cutting edge is smooth, the roundness is good, the taper is smaller, the cracking probability is low, almost no heat affected zone exists, the edge is not yellow, almost no damage is caused to the ceramic substrate, and the yield is greatly improved.)

1. The utility model provides a porous array picosecond laser galvanometer scanning drilling system of ceramic substrate which characterized in that includes: the device comprises a scanning galvanometer (1), a scanning laser beam unit (2), a substrate (3), an xy two-dimensional sliding table (4), a layered processing path (5), a processing hole site (6), a visual part (8), a protective gas nozzle (9) and a smoke suction cover (10);

the scanning galvanometer (1) is arranged at the upper part of the ceramic substrate porous array picosecond laser galvanometer scanning drilling system;

the scanning galvanometer (1) is connected with a visual component (8);

the xy two-dimensional sliding table (4) is arranged at the lower part of the ceramic substrate porous array picosecond laser galvanometer scanning drilling system;

the substrate (3) is arranged above the xy two-dimensional sliding table (4);

the scanning laser beam (2) is arranged between the scanning galvanometer (1) and the substrate (3);

the protective gas nozzle (9) and the smoke suction hood (10) are arranged above the substrate (3);

and the layered processing path (5) and the processing hole position (6) are arranged above the xy two-dimensional sliding table (4).

2. The picosecond laser galvanometer scanning drilling system for the porous array of the ceramic substrate according to claim 1, wherein the substrate (3) is a ceramic substrate.

3. The picosecond laser galvanometer scanning drilling system for the porous array of the ceramic substrate according to claim 1, wherein the vision component (8) adopts a CCD vision camera component.

4. The picosecond laser galvanometer scanning drilling system for the porous array of the ceramic substrate according to claim 1, further comprising: protecting the air pipe;

the protective gas nozzle (9) is connected with a protective gas pipe.

5. The picosecond laser galvanometer scanning drilling system for the porous array of the ceramic substrate according to claim 4, further comprising: protecting the gas cylinder;

the protection air pipe is connected with the protection air pipe.

6. A method for drilling holes on a ceramic substrate by scanning a picosecond laser galvanometer in a porous array is characterized in that the system for drilling holes on the ceramic substrate by scanning the picosecond laser galvanometer in the porous array of the ceramic substrate as in claims 1-5 is adopted, and comprises the following steps:

step S1: setting a laser drilling and cutting processing path and laser drilling and cutting process parameters, and acquiring cutting process control information and cutting path control information;

the cutting process control information directs a cutting process of laser drilling;

the cutting path control information guides a cutting processing path of the laser drilling;

step S2: during drilling, the xy axis of the station sliding table moves a to-be-drilled hole of the ceramic substrate to a drilling position;

step S3: automatically calculating the position of the hole to be drilled, and acquiring the position information of the hole to be drilled;

step S4: and drilling the substrate layer by layer according to the cutting process control information, the cutting path control information and the drilling path parameters.

7. The picosecond laser galvanometer scanning drilling method for the porous array of the ceramic substrate according to claim 6, wherein the step S3 comprises:

step S3.1: the CCD vision camera shooting component shoots images, and the machine vision software automatically calculates the position of the hole to be drilled and acquires the position information of the hole to be drilled.

8. The method for picosecond laser galvanometer scanning drilling of the porous array of the ceramic substrate according to claim 6, further comprising:

step S5: and starting a smoke dust suction device, opening a protective cutting area by protective gas, moving the Z axis of the cutting head downwards by one machining layer thickness when each layer is machined, scanning by a vibrating mirror to machine the holes again until all layers are machined, and closing laser.

9. The method for picosecond laser galvanometer scanning drilling of the porous array of the ceramic substrate according to claim 8, further comprising:

step S6: and (4) moving the workpiece to the drilling position of the next hole by the xy axis of the station sliding table, and repeating the step S4 and the step S5 until all the holes on the ceramic substrate are cut.

10. The picosecond laser galvanometer scanning drilling method for the porous array of the ceramic substrate according to claim 6, wherein the cutting process control information comprises any one or more of the following:

-laser power control information;

-laser pulse repetition frequency control information;

-pulse width control information;

-hierarchical quantity control information;

-cutting head down distance control information;

the cutting path control information includes any one or more of:

-cutting sequence control information for individual wells of the multi-well array;

-cutting centre coordinate control information.

Technical Field

The invention relates to the field of laser processing, in particular to a system and a method for scanning and drilling a ceramic substrate porous array picosecond laser galvanometer.

Background

The ceramic materials such as alumina and aluminum nitride have the advantages of high heat conductivity, high insulation degree, high temperature resistance and the like, and are widely applied to the fields of electronics and semiconductors. However, ceramic materials have high hardness and brittleness, and are difficult to mold, particularly, to form micropores. Because the laser has high power density and good directivity, the ceramic plate is generally processed by punching the ceramic substrate by the laser at present, a pulse laser or a quasi-continuous laser is generally adopted at present, the laser beam is focused on a workpiece which is vertically arranged with a laser shaft through an optical system, the laser beam with high energy density (105 and 109W/cm2) is emitted to melt the material, the material is gasified, the air flow which is generally coaxial with the laser beam is ejected by a laser cutting head, and the melted material is blown out from the bottom of a cut to form a through hole step by step. Traditional continuous laser, pulse laser and nanosecond laser, laser instantaneous peak power is lower, and the duration is longer, and the cutting round hole tapering is great, and the circularity is relatively poor, and the heat affected zone at edge is great, to the ceramic packaging technique of current rapid development, especially the following 5G field to devices such as pottery ultra-precision punching, cutting and even welded demand can not follow the development of market. The picosecond laser duration is only picosecond level, the instantaneous peak power of the laser can reach GW level, perfect cutting can be realized on devices such as glass and ceramics, almost no inclination angle exists, no heat influence area exists, the fragmentation rate is low, and the picosecond laser has very wide market application prospect in the fields of future 3C and medicine, particularly 5G communication.

Patent document CN110605488A discloses a ceramic laser drilling device, which adopts a three-axis laser drilling system with xy + cyclotron vibration for ceramic drilling of electronic and semiconductor devices, but does not refer to what kind of laser is adopted, and does not describe the drilling process specifically, and in addition, a circle with a larger diameter is cut through the cyclotron motion, and the cutting efficiency is low due to the inertia of the machine itself.

Patent document CN105499812A discloses a method for improving the processing quality of a ceramic heat dissipation substrate, and the invention relates to a laser processing method of an LED ceramic heat dissipation substrate, which mainly adopts a mode of coating a dye in advance, then drying, drilling holes and then cleaning to solve the problems of oxidation, yellowing and the like of the ceramic substrate in the drilling process, although the processing quality is improved, the working procedures are obviously increased, the processing efficiency is reduced, and in addition, the adopted laser is also a conventional continuous solid-state laser.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a system and a method for drilling a ceramic substrate porous array through scanning of a picosecond laser galvanometer.

The invention provides a ceramic substrate porous array picosecond laser galvanometer scanning drilling system, which comprises: the device comprises a scanning galvanometer 1, a scanning laser beam unit 2, a substrate 3, an xy two-dimensional sliding table 4, a layered processing path 5, a processing hole position 6, a porous array processing path 7, a visual part 8, a protective gas nozzle 9 and a smoke dust suction cover 10; the scanning galvanometer 1 is arranged at the upper part of the ceramic substrate porous array picosecond laser galvanometer scanning drilling system; the scanning galvanometer 1 is connected with a visual component 8; the xy two-dimensional sliding table 4 is arranged at the lower part of the ceramic substrate porous array picosecond laser galvanometer scanning drilling system; the substrate 3 is arranged above the xy two-dimensional sliding table 4; the scanning laser beam 2 is arranged between the scanning galvanometer 1 and the substrate 3; the protective gas nozzle 9 and the smoke suction hood 10 are arranged above the substrate 3; the layered processing path 5 and the processing hole position 6 are arranged above the xy two-dimensional sliding table 4.

Preferably, the substrate 3 is a ceramic substrate.

Preferably, the vision part 8 adopts a CCD vision camera part.

Preferably, the method further comprises the following steps: protecting the air pipe; the protective gas nozzle 9 is connected with a protective gas pipe.

Preferably, the method further comprises the following steps: protecting the gas cylinder; the protection air pipe is connected with the protection air pipe. The protective gas nozzle and the smoke suction hood are arranged at the workpiece cutting position. The protection air tap is connected with a protection air pipe, and the protection air pipe is connected with a protection air bottle. When drilling, the protective gas and the smoke suction are opened, the protective gas protects the ceramic substrate punching area, the ceramic surface is prevented from being oxidized and yellowed in the ceramic drilling process, the performance is influenced, the appearance is attractive, smoke generated during cutting is sucked through the smoke suction cover, the laser absorption rate of a workpiece is improved, and the work environment is purified.

According to the invention, the method for drilling holes by scanning the ceramic substrate porous array picosecond laser galvanometer adopts a ceramic substrate porous array picosecond laser galvanometer scanning drilling system, and comprises the following steps: step S1: setting a laser drilling and cutting processing path and laser drilling and cutting process parameters, and acquiring cutting process control information and cutting path control information; the cutting process control information directs a cutting process of laser drilling; the cutting path control information guides a cutting processing path of the laser drilling; step S2: during drilling, the xy axis of the station sliding table moves a to-be-drilled hole of the ceramic substrate to a drilling position; step S3: the CCD vision is used for shooting images, and the machine vision software automatically calculates the position of the hole to be drilled to obtain the position information of the hole to be drilled; step S4: and drilling the substrate layer by layer according to the cutting process control information, the cutting path control information and the drilling path parameters.

Preferably, the step S3 includes: step S3.1: the CCD vision camera shooting component shoots images, and the machine vision software automatically calculates the position of the hole to be drilled and acquires the position information of the hole to be drilled.

Preferably, the method further comprises the following steps: step S5: and starting a smoke dust suction device, opening a protective cutting area by protective gas, moving the Z axis of the cutting head downwards by one machining layer thickness when each layer is machined, scanning by a vibrating mirror to machine the holes again until all layers are machined, and closing laser.

Preferably, the method further comprises the following steps: step S6: and (4) moving the workpiece to the drilling position of the next hole by the xy axis of the station sliding table, and repeating the step S4 and the step S5 until all the holes on the ceramic substrate are cut.

Preferably, the cutting process control information includes any one or more of: -laser power control information; -laser frequency control information; -pulse width control information; -hierarchical quantity control information; -cutting head down distance control information; the cutting path control information includes any one or more of: -cutting sequence control information for individual wells of the multi-well array; -cutting centre coordinate control information.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention adopts picosecond laser to cut the ceramic substrate, the edge is smooth, the roundness is good, the taper is smaller, the fragmentation rate is low, the edge almost has a heat affected zone, the edge does not yellow, the ceramic substrate is not damaged, and the yield is greatly improved;

2. the invention is particularly suitable for the high-precision application of 5G current ceramic substrates;

3. the invention can solve the processing of the porous array on the ceramic substrate at one time through the adjustment of the xy precision sliding table, simultaneously solves the edge cutting effect caused by laser inclination, and improves the roundness and the taper of the drilled hole;

4. according to the invention, the laser galvanometer scans the laser beam, so that the direct scanning cutting of a large aperture in a certain range can be realized without moving the sliding table, and the response speed and the cutting speed are improved;

5. in the invention, the CCD vision automatically identifies and positions the cutting position, thereby obviously improving the processing efficiency and the position precision and reducing the position deviation possibly caused by human factors.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of a porous array of a ceramic substrate processed layer by laser galvanometer scanning according to an embodiment of the present disclosure.

FIG. 2 is a schematic diagram of a cutting path of a ceramic porous array according to an embodiment of the present invention.

FIG. 3 is a flowchart of a drilling process of the galvanometer scanning ceramic porous array according to an embodiment of the present invention.

In the figure:

scanning galvanometer 1 processing hole site 6

Multi-aperture array processing path 7 of scanning laser beam unit 2

Visual component 8 of substrate 3

xy two-dimensional sliding table 4 protection gas nozzle 9

Fume extraction hood 10 for layered processing path 5

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

The invention provides a ceramic substrate porous array picosecond laser galvanometer scanning drilling system, which comprises: the device comprises a scanning galvanometer 1, a scanning laser beam unit 2, a substrate 3, an xy two-dimensional sliding table 4, a layered processing path 5, a processing hole position 6, a porous array processing path 7, a visual part 8, a protective gas nozzle 9 and a smoke dust suction cover 10; the scanning galvanometer 1 is arranged at the upper part of the ceramic substrate porous array picosecond laser galvanometer scanning drilling system; the scanning galvanometer 1 is connected with a visual component 8; the xy two-dimensional sliding table 4 is arranged at the lower part of the ceramic substrate porous array picosecond laser galvanometer scanning drilling system; the substrate 3 is arranged above the xy two-dimensional sliding table 4; the scanning laser beam 2 is arranged between the scanning galvanometer 1 and the substrate 3; the protective gas nozzle 9 and the smoke suction hood 10 are arranged above the substrate 3; the layered processing path 5 and the processing hole position 6 are arranged above the xy two-dimensional sliding table 4.

Preferably, the substrate 3 is a ceramic substrate.

Preferably, the vision part 8 adopts a CCD vision camera part.

Preferably, the method further comprises the following steps: protecting the air pipe; the protective gas nozzle 9 is connected with a protective gas pipe.

Preferably, the method further comprises the following steps: protecting the gas cylinder; the protection air pipe is connected with the protection air pipe. The protective gas nozzle and the smoke suction hood are arranged at the workpiece cutting position. The protection air tap is connected with a protection air pipe, and the protection air pipe is connected with a protection air bottle. When drilling, the protective gas and the smoke suction are opened, the protective gas protects the ceramic substrate punching area, the ceramic surface is prevented from being oxidized and yellowed in the ceramic drilling process, the performance is influenced, the appearance is attractive, smoke generated during cutting is sucked through the smoke suction cover, the laser absorption rate of a workpiece is improved, and the work environment is purified.

Specifically, in one embodiment, a ceramic substrate porous array picosecond laser galvanometer scanning drilling system cuts 2mm thick ceramic. Cutting according to the following parameters: the speed is 1200mm per second, the frequency is 100hz, the pulse width is 15ps, the power is 70%, and the layered cutting is carried out for 30 times.

Preferably, the laser generator generates an ultraviolet picosecond laser having a wavelength of 300-. The average laser power is 5-50W, the laser pulse repetition frequency is 10-1MHz, and the pulse width is less than 15 ps. The method specifically comprises the following steps: ultraviolet picosecond laser with the wavelength of 355nm and the laser power of 30W.

Laser cutting head facula diameter be 15um, the focus is 100 mm.

Work platform include the accurate slip table of xy diaxon and a special tool of placing the work piece, slip table stroke range is 100mmx100mm, repetition precision is for being less than or equal to 1um, positioning accuracy is for being less than or equal to 3um for the accurate regulation of work piece position.

The CCD visual positioning precision can reach less than or equal to +/-5 um

The cutting speed of the laser galvanometer is 100-3000 mm/s adjustable, and a hole smaller than 40mmX40mm can be directly cut without xy-axis movement of a station sliding table.

According to the invention, picosecond laser is adopted to drill the porous array of the ceramic substrate layer by layer, and the porous array is automatically positioned through the adjustment of an xy precision sliding table; the direct scanning cutting of big aperture in certain range can be realized through the galvanometer and xy axle that need not remove the slip table has improved response speed and cutting speed, and CCD vision is automatic discerns and fixes a position the cutting position, is showing and is improving machining efficiency and position accuracy, has also reduced the positional deviation that artificial factor probably leads to. The invention fully utilizes the ultrashort and ultrastrong characteristic of picosecond laser, instantly melts and gasifies ceramic materials, overcomes the problem of ceramic fragmentation in the conventional laser cutting, has smooth cutting edge, good roundness, smaller taper and low fragmentation probability, has no thermal influence area on the boundary, does not yellow the edge, almost has no damage to the ceramic substrate, greatly improves the yield, and is particularly suitable for the high-precision application of the ceramic substrates of 5G and the like.

According to the invention, the method for drilling holes by scanning the ceramic substrate porous array picosecond laser galvanometer adopts a ceramic substrate porous array picosecond laser galvanometer scanning drilling system, and comprises the following steps: step S1: setting a laser drilling and cutting processing path and laser drilling and cutting process parameters, and acquiring cutting process control information and cutting path control information; the cutting process control information directs a cutting process of laser drilling; the cutting path control information guides a cutting processing path of the laser drilling; step S2: during drilling, the xy axis of the station sliding table moves a to-be-drilled hole of the ceramic substrate to a drilling position; step S3: the CCD vision is used for shooting images, and the machine vision software automatically calculates the position of the hole to be drilled to obtain the position information of the hole to be drilled; step S4: and drilling the substrate layer by layer according to the cutting process control information, the cutting path control information and the drilling path parameters.

Preferably, the step S3 includes: step S3.1: the CCD vision camera shooting component shoots images, and the machine vision software automatically calculates the position of the hole to be drilled and acquires the position information of the hole to be drilled.

Preferably, the method further comprises the following steps: step S5: and starting a smoke dust suction device, opening a protective cutting area by protective gas, moving the Z axis of the cutting head downwards by one machining layer thickness when each layer is machined, scanning by a vibrating mirror to machine the holes again until all layers are machined, and closing laser.

Preferably, the method further comprises the following steps: step S6: and (4) moving the workpiece to the drilling position of the next hole by the xy axis of the station sliding table, and repeating the step S4 and the step S5 until all the holes on the ceramic substrate are cut.

Preferably, the cutting process control information includes any one or more of: -laser power control information; -laser frequency control information; -pulse width control information; -hierarchical quantity control information; -cutting head down distance control information; the cutting path control information includes any one or more of: -cutting sequence control information for individual wells of the multi-well array; -cutting centre coordinate control information.

Specifically, in one embodiment, a method for drilling a porous array of a ceramic substrate by picosecond laser galvanometer scanning is realized by galvanometer scanning, ultrafast laser, CCD vision and fine position adjustment of an xyz axis, and includes:

the basic method comprises the following steps: the hole to be drilled is divided into a plurality of machining layers, laser layer-by-layer machining is carried out, and each hole is adjusted according to a certain sequence through a station sliding table xy axis. Firstly, setting a laser drilling processing path and laser drilling process parameters, moving a to-be-drilled hole of a ceramic substrate to a drilling position by a station sliding table xy axis during drilling, then shooting an image by CCD vision, automatically calculating the to-be-drilled hole position by machine vision software, then precisely drilling the ceramic substrate layer by a vibrating mirror laser beam, simultaneously starting a smoke suction device, opening a protective cutting area by protective gas, moving a processing layer thickness downwards by a cutting head Z axis every layer to be processed, scanning by a vibrating mirror to process the hole again until all layers are processed, and closing the laser; and then, moving the workpiece to the drilling position of the next hole by the xy axis of the station sliding table, and repeating the steps until all the holes on the ceramic substrate are cut.

The processing path comprises a cutting sequence of each hole of the multi-hole array and cutting center coordinates; and configuring laser drilling process parameters of each hole according to the drilling path, wherein the laser drilling process parameters comprise laser power, laser frequency, pulse width, layering quantity and cutting head downward moving distance.

Further, the laser process parameters also include the galvanometer scanning path of each hole, the on/off sequence and the position of the laser.

The laser generator is an ultraviolet picosecond and femtosecond laser with the wavelength of 300-.

Preferably, the laser cutting head is a 2-axis or even 3-axis galvanometer cutting head, and is particularly characterized in that laser is reflected by the x-axis galvanometer lens and the y-axis galvanometer lens and then focused on a workpiece through the focusing lens, and the cutting path of the laser beam can be rapidly changed by respectively controlling the angles of the z-axis galvanometer lens and the y-axis galvanometer lens. When the processing aperture is not more than 40mmx40mm, the galvanometer scanning laser beam can be directly processed without moving the xy axis of the workpiece sliding table.

Furthermore, laser generated by the laser generator is collimated and focused by a vibrating mirror to be a light spot diameter not larger than 0.015 mm.

The working platform is characterized by comprising an xy two-axis precise sliding table and a special jig for placing a workpiece, wherein the special jig is fixedly connected to the upper sliding table and used for placing a drilled ceramic substrate. When drilling, the xy-axis translation of the sliding table can adjust the position of the cutting center of the belt drilling to the laser, so that the sequential processing of the hole arrays on the ceramic substrate is realized, the edge cutting effect possibly brought by laser oblique cutting is eliminated, and the size precision of drilling is improved.

Preferably, the laser cutting head is provided with a CCD vision camera system, directly shoots laser and a processing area of a workpiece, and accurately positions the relative position of the hole to be drilled relative to the cutting center through image processing, feature extraction and position calculation.

The thickness of the lower moving machining layer of the cutting head is determined by a process experiment, and the lower moving machining layer is characterized in that: when each layer is processed, the cutting head moves downwards to enable the focus of the laser to move downwards to the corresponding processing layer.

Preferably, the shielding gas nozzle and the smoke suction hood are arranged at a workpiece cutting position. The protection air tap is connected with a protection air pipe, and the protection air pipe is connected with a protection air bottle. When drilling, the protective gas and the smoke suction are opened, the protective gas protects the ceramic substrate punching area, the ceramic surface is prevented from being oxidized and yellowed in the ceramic drilling process, the performance is influenced, the appearance is attractive, smoke generated during cutting is sucked through the smoke suction cover, the laser absorption rate of a workpiece is improved, and the work environment is purified.

The invention adopts picosecond laser to cut the ceramic substrate, the edge is smooth, the roundness is good, the taper is smaller, the fragmentation rate is low, the edge almost has a heat affected zone, the edge does not yellow, the ceramic substrate is not damaged, and the yield is greatly improved; the invention is particularly suitable for the high-precision application of 5G current ceramic substrates; the invention can solve the processing of the porous array on the ceramic substrate at one time through the adjustment of the xy precision sliding table, simultaneously solves the edge cutting effect caused by laser inclination, and improves the roundness and the taper of the drilled hole; according to the invention, the laser galvanometer scans the laser beam, so that the direct scanning cutting of a large aperture in a certain range can be realized without moving the sliding table, and the response speed and the cutting speed are improved; in the invention, the CCD vision automatically identifies and positions the cutting position, thereby obviously improving the processing efficiency and the position precision and reducing the position deviation possibly caused by human factors.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.